Approximately 15% of couples attempting their first pregnancy do not succeed. Most authorities define these individuals as infertile if they have been unable to achieve a pregnancy after one year of unprotected intercourse. Conception normally is achieved within twelve months in 80-85% of couples who use no contraceptive measures, and persons not conceiving after this time should therefore be regarded as possibly infertile and should be evaluated. Data available over the past twenty years reveal that in approximately 30% of cases pathology is found in the man alone, and in another 20% both the man and woman are abnormal. Therefore, the male factor is at least partly responsible in about 50% of infertile couples.
Sperm are produced by repeated division of cells in small coiled tubules within the testes at a rate of appropriately 100 million per day. Sperm production is a lengthy process, from the beginning of division of the stem cell to the appearance of mature sperm in the semen takes about 3 months. The sperm spend 2 to 10 days passing through the epididymis, during which time they mature and become capable of swimming and fertilising eggs. The volume of liquid from the testes and epididymides is less than 5% of the total semen volume. About 65% of the semen volume comes from the seminal vesicles and 25% from the prostate gland. The average semen volume for healthy men ejaculating every two days is 3 ml and the sperm concentration 85 million per ml. During ejaculation the sperm and the prostatic fluid come out first and the seminal vesicle fluid follows. The seminal vesicle fluid coagulates giving the semen a lumpy gel-like appearance. After 10 minutes or so liquefaction occurs and the gel disappears.
Male infertility may be caused by many conditions that affect the production of functional sperm. The most common cause is varicocele (i.e. hardening of the veins that drain the testes) which accounts for about 40% of cases and is treated surgically. Testicular failure accounts for approximately 10% of cases and may result from numerous causes including malignancy, mumps, Kleinfelter's syndrome, injury, and radio- or chemotherapy. Hyperspermia, increased seminal fluid volume, also accounts for about 10% of cases. Endocrine diseases affecting spermatogenesis account for approximately 9% of cases and usually involve pituitary or adrenal hypoplasia or hyperthyroidism. Obstruction of the ejaculatory duct accounts for about 5% of cases and sperm autoantibodies for 1 to 2%.
Approximately 13% of men have untreatable sterility, 11% have treatable conditions and 76% have disorders of sperm production or function which do not usually have clearly defined effective treatments. Of the 13% of men with untreatable sterility, most have no sperm in their semen (azoospermia) because the tubules in the testes which produce sperm did not develop or have been irreversibly damaged. This may be associated with failure of the testes to descend into the scrotum during childhood, inflammation of the testes or treatment with certain drugs. In some sterile men, sperm are produced in normal numbers, but they are either not motile (i.e. do not swim) or lack structures necessary for penetration and fertilisation of eggs which may be detected by microscope examination of the shape of the sperm and reported as abnormal morphology. Some men with failure of sperm production do not produce normal amounts of the male sex hormone, testosterone, and their general health and sexual performance is improved by treatment with testosterone. Over three quarters of men investigated for infertility have sperm present in the semen, but in lower numbers than normal—oligospermia (38%), or in adequate numbers but with reduced motility (33%).
Oligospermia is a condition associated with an abnormally low number of sperm in the ejaculate of the male. The normal range of sperm count is between 20 million/ml and 200 million/ml. The finding that the sperm count is below 20 million/ml indicates oligospermia. Common causes of oligospermia are stress, smoking of tobacco (nicotine damages sperms), lead (workers in printing press have low sperm count), hot climates, saunas, hot baths, the wearing of tight underwear, and other situations in which scrotal temperature may be raised, varicocele and consumption of alcohol.